The change of volatile compounds of two kinds of vinasse-cured ducks during processing.

Vinasse-cured duck was processed by boiling, salting, and vinasse-dry-curing or vinasse-wet-curing. Volatile compounds, moisture contents, reducing sugars, and thiobarbituric acid reactive substances (TBARS) values during processing were determined. Reducing sugars decreased during boiling and increased after vinasse-curing. TBARS values increased throughout the processing. The volatiles of ducks during processing and vinasse-curing agents (dry vinasse and vinasse sauce) were 125 compounds. The first principal component (PC1) belonged to the flavor of cooked duck, whereas the second principal component (PC2) represented the flavor of yellow rice wine. The 66.49 and 29.61% of typical aroma of vinasse-dry-cured product were from dry vinasse and lipid oxidation, respectively, whereas the 75.58 and 21.89% of aroma of vinasse-wet-cured product were from vinasse sauce and lipid oxidation, respectively. Lipid oxidation products increased after boiling, whereas salting promoted their release. Compared with vinasse-wet-cured duck, vinasse-dry-cured product presented richer aroma of lipid oxidation and weaker flavor of vinasse-curing agents. Besides, protein denaturation which was caused by ethanol could influence the retention and release of flavor. In conclusion, two kinds of vinasse-curing methods influenced the characteristic volatiles of products and their generation during processing.

Effect of pH on the interaction of volatile compounds with the myofibrillar proteins of duck meat.

In order to clarify the influence of curing agents on the flavor of duck, the effect of pH on the surface hydrophobicity, secondary structures, and adsorption capacity of myofibrillar proteins to alcohols, aldehydes, ketones, and esters was assessed using Raman spectroscopy, gas chromatography-mass spectrometer, and other methodologies. The hydrophobicity decreased as pH increased from 5.0 to 8.0; ß-turn turned into α-helix and random coil as pH increased from 5.0 to 7.0, while α-helix and random coil turned into ß-sheet and ß-turn as pH increased from 7.0 to 8.0. With the increase of pH, the decreased adsorbing of alcohols could depend on hydrogen bonds. As pH increased from 5.0 to 8.0, the increase of aldehydes and esters was attributed to the unfolding of myofibrillar proteins and decreased hydrophobicity. The decreased adsorbing of ketones was due to the decreased hydrophobicity as pH increased from 5.0 to 8.0. The present work provided information about the correlation between structure and adsorption capacity of myofibrillar proteins to flavor compounds.